Niels Bohr’s Theory of Atoms and Molecules: The Role of Experiments

Lecturer:

Helge Kragh

First encounter

Lecture in Memory of Professor Mara Beller

The theory of the constitution of atoms and molecules that the theorist Niels Bohr proposed nearly a century ago was not motivated by specific empirical problems. However, he did follow relevant experiments closely, and for a period he himself also engaged in experimental work. The development of Bohr's theory illustrates the fertility of a close connection between experiment and theory; it also illustrates the complex role played by empirical successes and anomalies in theory testing. But empirical successes, theory confirmation, and anomalies may be given different weights – not always for good reasons. Why this is so, and how an experimental situation affects physicists’ evaluation of a theory and its replacement, will be illustrated by the transition of the old quantum theory to the new quantum